Safety profile of topical diclofenac: a meta-analysis of blinded, randomized, controlled trials in musculoskeletal conditions

Background: Topical non-steroidal anti-inflammatory drugs (NSAIDs) are clinically proven for the management of musculoskeletal conditions. It is important that prescribers and patients are aware of the safety profile of topical NSAIDs. Objectives: To evaluate the risk of adverse events (AEs) associated with topical diclofenac for the treatment of acute and chronic musculoskeletal conditions. Design: Systematic review and meta-analysis of blinded, randomized, placebo-, vehicle- or active-controlled trials. Results: The risk of any type of AE experienced with topical diclofenac was slightly higher compared with placebo/vehicle (RR 1.11), but was more than 50% lower than the risk observed with active topical comparators (RR 0.53). Absolute risk values indicated differences in the risk of AEs depending on the diclofenac formulation used; in particular, lower rates of local skin reactions were observed with diclofenac patches (e.g. 2.5% in placebo/vehicle-controlled studies) and gels (4.2%) compared with diclofenac solutions containing dimethylsulfoxide (34.2%). Dry skin/crusting and rash were the most common local skin reactions reported (9.0% and 3.0% of patients, respectively, in placebo/vehicle-controlled studies), which were usually mild-to-moderate and self-resolving. The discontinuation rate due to local skin reactions with topical diclofenac (1.9%) was low and comparable with non-active comparators (0.7%), and the tolerability of topical diclofenac treatment was rated as ‘good’ to ‘excellent’ by >90% physicians and patients. Conclusions: Topical diclofenac appears to be generally well tolerated for cutaneous use in acute and chronic musculoskeletal conditions